There are really stones known as "trovants" in Romania, that grow, move, and even reproduce. They take in the minerals from the rain after each heavy downpour, which combine with the chemicals already existing in the rock to produce a reaction and pressure within that eventually causes the stone to grow and reproduce.
The meteor crash is footage of the spaceship crash from It Came from Outer Space (1953) which Universal produced four years earlier.
The town of San Angelo is the Universal Studios back lot, the "Courthouse Square Lot" to be specific. It's the same lot used in 1985's "Back to the Future" and its buildings/courthouse are highly recognizable.
William Schallert has an uncredited role as the US Weather Bureau forecaster.
Voice actor Paul Frees intones the ominous introductory narration. Frees was known for his villainous or serious voice portrayals, while fellow specialists Mel Blanc and Daws Butler provided more humorous characterizations.